This special double issue of Mosaic on “Other Worlds” is, as Ray Bradbury writes, a keystone issue that, like fantasy and science fiction, simultaneously looks backward and forward at the history and future of ideas and metaphor. These essays boldly go into the old and new spaces of genre, myth, and imagination by examining topics such as the utility of science fiction, the small number of female science fiction writers, and imagining otherness. The issue provides examinations of many key authors in these genres, including Arthur C. Clarke, Ursula K. Le Guin, Samuel R. Delany, Jorge Luis Borges, M.C. Escher, Doris Lessing, Peter Beagle, Olaf Stepledon, C.S. Lewis, Frank Herbert, and Ray Bradbury.